1. Field of the Invention
The present invention relates generally to spray cool thermal management devices and more specifically it relates to a hybrid thermal management system for providing simultaneous global spray cooling and zone cooling for a plurality of electronic cards.
2. Description of the Related Art
The present invention relates to the thermal management of electronic components that are mounted upon electronic cards (a.k.a. expansion boards) or substrates. In a card level system, a plurality of cards are electrically connected within sockets upon a backplane (e.g. motherboard, etc.). Electronic cards are utilized in various applications such as personal computers, workstations, server computers, rack mounted services, network routers, network switches, telephone equipment (DWDMs, ADMs, TDMs, switches, repeaters and the like), and military applications (vehicle, aircraft, etc.). Examples of electronic cards include but are not limited to modems, video processors, network interfaces, processors, memory, hard drive controllers, hard drives, mouse controller, keyboard controller, global position systems, wireless cards, backplane controller cards and the like.
“Dry cooling” (i.e. air cooling) has been in usage for years for cooling electronic components. An example of a dry cooling system is a conventional desktop computer with a fan that passes air over the electronic components to cool the same. Dry cooling technology is acceptable for low powered electronic components. Dry cooling may also include standard conduction card cooling methods wherein a card creates a heat conduction path between one or more components to be cooled located on the card and a wall of a chassis.
Modern electronic devices have increased thermal management requirements. Conventional dry cooling technology simply is not capable of efficiently cooling modern high-end electronics. “Spray cooling” is being adopted today as the most efficient option for thermally managing electronic systems. U.S. Pat. No. 5,220,804 entitled High Heat Flux Evaporative Spray Cooling to Tilton et al. describes the earlier versions of spray cooling technology. U.S. Pat. No. 6,108,201 entitled Fluid Control Apparatus and Method for Spray Cooling to Tilton et al. also describes the usage of spray cooling technology to cool a printed circuit board. Spray cooling may be performed locally (i.e. where the chip is sprayed directly), globally (i.e. where the chip and surrounding electronics/boards are also sprayed), a combination of locally and globally, or in conjunction with air cooling or other cooling methods.
While there are many benefits in utilizing spray cooling technology, there are some detriments. One of the detriments with spray cooling technology is the relatively high cost of creating a spray cooling system capable of thermally managing all of the electronic devices, electronic cards and the like for an electronic system. Another problem with spray cooling technology is the potential increased weight of the thermal management unit. A further problem with spray cooling technology is that not all electronic devices are suitable for usage within a liquid coolant environment. Another problem with spray cooling technology is that to replace, repair or test any electronic device within a spray chassis the seal must be broken to the spray chassis thereby leading to the loss of coolant.
While these devices may be suitable for the particular purpose to which they address, they are not as suitable for providing simultaneous spray cooling and dry cooling for a plurality of cards sharing a common backplane, or backplane assembly. Conventional thermal management systems are suitable only for low or high heat flux applications with no thermal management system serving the need of being optimized for applications where some electronic devices may be cooled by global spray cooled, zone cooled and air cooled.
In these respects, the hybrid thermal management system according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of providing simultaneous spray cooling and dry cooling for a plurality of cards sharing a common backplane.